Percutaneous transluminal coronary angioplasty is frequently used in treating coronary atherosclerosis which produces areas of blockage within a coronary artery. However, before performing percutaneous transluminal coronary angioplasty, and during the procedure itself, iodine containing dye or other contrast material is injected into a patient's artery through a catheter. This iodine solution is fluorescent and enables the coronary arteries to be clearly illustrated for the physician.
However, there is one serious problem associated with the use of contrast solutions. The problem is that the use of such solutions may lead to contrast induced nephropathy. Contrast induced nephropathy can result in transient or permanent renal impairment or failure of a patient's kidneys. It is well known that renal dysfunction is associated with the use of radio graphic contrast media and that the dysfunction may range from a transient slight increase in serum creatinine levels to renal failure requiring transient or long-term dialysis.
Many patients require revascularization of more than a single vessel. However, when there is danger of contrast induced renal failure, the vessels are done on separate procedures at greatly increased cost and additional risk of arterial puncture. Therefore, it is highly desirable or imperative to eliminate the risk of renal failure.
Further, there are many other patients with chronic renal insufficiencies who must wait 24 to 48 hours in the hospital before undergoing percutaneous transluminal coronary angioplasty in order to space the kidney load associated with the contrast load. Still others, particularly the elderly with a pre-existing renal insufficiency make up a large group in which angioplasty is avoided because multi-vessel disease and multi-vessel intervention may lead to renal failure.
In view of the above, several attempts have been made to prevent contrast associated nephropathy. For example, a U.S. Pat. No. 6,554,819 discloses a method and device for preventing contrast associated nephropathy. As disclosed therein, when a contrast solution is injected into the coronary artery of a patient, blood is prevented from flowing through the coronary sinus into the right atrium. The blood in the coronary sinus is bypassed to a filtration device which filters out the contrast solution from the blood and re-circulates the blood back to the patient. Preferably, blood flow from the coronary sinus is blocked by a balloon catheter which includes a port distal of the balloon so that when the sinus is occluded, blood flows from the sinus into the central lumen of the catheter where it can be directed to the filtration device.
A more recent approach for removal of radio-contrast media from blood is set forth in a U.S. Pat. No. 7,163,520 of Bernard et al. The Bernard patent discloses an extra corpeal blood circuit for removal of contrast from human blood using a filter and withdraw filter pump and a bypass pump. The withdrawal filter blood pump operates when a contrast bolus has been detected. Otherwise, the bypass blood pump maintains physiological blood flow from the coronary sinus preventing the need for deflation and re-inflation of the balloon catheter. When contrast is detected in the patient's blood, the bypass blood pump is stopped to prevent contrast from leaking back into the patient's circulatory system via the bypass pump and coronary sinus blood flow is maintained at its physiological blood flow resulting in the heart being oblivious to the transition by the pre-filter blood pump.
Notwithstanding the above, it is presently believed that there is a need for an improved method and system for preventing contrast associated nephropathy. There should be a need since the method and apparatus in accordance with the present invention facilitates removal of the contrast media and at the same time reduces the risk of contrast associated nephropathy. Therefore, it is believed that more procedures can be completed on patients that are at risk for renal damage.